Densely Arrayed Cage-Shaped Polymer Topologies Synthesized via Cyclopolymerization of Star-Shaped Macromonomers

Abstract

This work reports a facile and versatile ring-opening metathesis polymerization of three-and four-armed star-shaped poly(ε-caprolactone) (PCL) macromonomers bearing a norbornenyl group at each chain end using Grubbs' third-generation catalyst under diluted condition to obtain graft polymers (GPs) comprising densely arrayed three-and four-armed cage-shaped grafted PCLs (GPCLs) with narrow dispersity (1.19−1.35) and a controllable number of cage repeating units up to 40 (molecular weight: ∼320 000 g mol −1 ). The GPCLs were characterized using nuclear magnetic resonance spectroscopy, size exclusion chromatography, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The cyclopolymerization proceeded via repetitive rapid intramolecular reactions to form cage-shaped units followed by slow intermolecular propagation. This synthesis was applicable to star-shaped poly(L-lactide), poly(trimethylene carbonate), and poly(ethylene glycol). Investigating the structure−property relationships regarding crystallization behavior, hydrodynamic diameter, and viscosity revealed that cageshaped topological side chains reduced the chain dimensions and mobility compared to their linear and cyclic counterparts.

Rotaxane Formation of Multicyclic Polydimethylsiloxane in a Silicone Network: A Step toward Constructing “Macro‐Rotaxanes” from High‐Molecular‐Weight Axle and Wheel Components

“…Although multicyclic polymer synthesis is challenging, we recently established a highly efficient synthetic pathway for multicyclic polymers that does not require a complicated multistep process. [34,35] Cyclopolymerization of α,ω-norbornenyl-functionalized macromonomers produces the desired multicyclic polymer with a controlled number of cyclic units and ring sizes via ring-opening metathesis polymerization (ROMP) using a Grubbs 3 rd -generation catalyst (G3) (Scheme 1a). This pathway affords multicyclic polymers in high yields from commercially available telechelic polymers in two steps, which is simpler than the synthesis of monocyclic polymers.…”

“…Herein, we report the topological trapping of multicyclic PDMS in silicone networks to experimentally determine the impact of cyclic polymer topology on trapping efficiency and investigate macro‐rotaxane formation. Although multicyclic polymer synthesis is challenging, we recently established a highly efficient synthetic pathway for multicyclic polymers that does not require a complicated multistep process [34, 35] . Cyclopolymerization of α,ω‐ norbornenyl‐functionalized macromonomers produces the desired multicyclic polymer with a controlled number of cyclic units and ring sizes via ring‐opening metathesis polymerization (ROMP) using a Grubbs 3 rd ‐generation catalyst (G3) (Scheme 1a).…”

Cage‐Shaped Polymers Synthesis: A Comprehensive State‐of‐the‐Art

“…Also, by further twisting the reaction conditions, the authors were able to create graft(cage‐shaped) polymers with M n,MALS up to 303 and 95 kg mol −1 for graft(3‐ and 4‐arm cage‐shaped) polymers, respectively ( Scheme ,I,II). [ 23 ]…”

“…Also, by further twisting the reaction conditions, the authors were able to create graft(cage-shaped) polymers with M n,MALS up to 303 and 95 kg mol −1 for graft(3-and 4-arm cageshaped) polymers, respectively (Scheme 6,I,II). [23] This major breakthrough is not only the first example of cages possessing more than four arms, but constitutes also an efficient way to synthetize polymer cages with virtually any number of arms. In fact, only the prerequisite to obtain defect-free polymer stars as well as end functionalization fidelity might limit the number of arms.…”

Precise Syntheses of Alternating Cyclocopolymers via Radical Copolymerizations of Divinyl Ether with N-Substituted Maleimides

“…Control of polymer topology is one of the most significant challenges in the field of polymer chemistry, and many attempts have been made to construct desired polymer topologies. So far, various types of “topological polymers” such as cyclic polymers, − cage polymers, − star-shaped polymers, (hyper)­branched or dendritic polymers, − ladder polymers, 2D sheet polymers, , and more complex polymers − have been successfully synthesized based on controlled polymerization (living polymerization) and/or the click reaction. , It has been also found that such topological polymers show topology-specific physical properties, and thus, topology-controlled polymers have a tremendous amount of potential for the development of novel polymer materials as well as for the elucidation of unsolved issues in polymer science.…”